Summary

A severe, often fatal, zoonotic infection caused by a virus of the Filoviridae family (genus
Ebolavirus
).

Human-to-human transmission occurs via contact with body fluids from infected patients. The incubation period after infection is 1 to 21 days (typically 5-12 days), and patients are not considered infectious until they develop symptoms.

Initial stages of infection are non-specific, which makes the differential diagnosis broad; therefore, clinical suspicion of the infection with prompt isolation is very important in the context of a history of exposure.

Management is centred around supportive care and infection control. The lack of any specific antiviral treatment or approved vaccine makes treatment difficult; however, several potential therapeutic agents are undergoing accelerated development, and clinical studies are either planned or ongoing.

The risk of sexual transmission from male survivors may persist for at least 9 months.

As there is a high likelihood of infected people travelling, all countries should have tested and practised protocols ready for screening and managing patients.

Definition

A severe, often fatal, zoonotic infection caused by infection by a virus of the Filoviridae family (genus
Ebolavirus
). There are currently 5 known species:
Zaire ebolavirus
,
Sudan ebolavirus
,
Tai Forest ebolavirus
,
Bundibugyo ebolavirus
, and
Reston ebolavirus
.
[1]Centers for Disease Control and Prevention. About Ebola virus disease. February 2016. http://www.cdc.gov/ (last accessed 19 July 2017).
http://www.cdc.gov/vhf/ebola/about.html
The
Zaire ebolavirus
is responsible for the outbreak that started in West Africa in 2014, the largest outbreak since the virus was first discovered in 1976.

The virus is thought to be initially acquired from infected animals such as bats and non-human primates, but has potential for human-to-human transmission. Transmission occurs by close contact with body fluids of infected patients. The incubation period after infection is 1 to 21 days (typically 5-12 days) in 95% of patients,
[2]World Health Organization. Are the Ebola outbreaks in Nigeria and Senegal over? October 2014. http://www.who.int/ (last accessed 19 July 2017).
http://www.who.int/mediacentre/news/ebola/14-october-2014/en/
[3]WHO Ebola Response Team. Ebola virus disease in West Africa: the first 9 months of the epidemic and forward projections. N Engl J Med. 2014;371:1481-1495.
http://www.nejm.org/doi/full/10.1056/NEJMoa1411100#t=article
http://www.ncbi.nlm.nih.gov/pubmed/25244186?tool=bestpractice.com
with a mean of 11.4 days in the 2014 outbreak.
[3]WHO Ebola Response Team. Ebola virus disease in West Africa: the first 9 months of the epidemic and forward projections. N Engl J Med. 2014;371:1481-1495.
http://www.nejm.org/doi/full/10.1056/NEJMoa1411100#t=article
http://www.ncbi.nlm.nih.gov/pubmed/25244186?tool=bestpractice.com
Incubation periods may be shorter in children.
[4]WHO Ebola Response Team. Ebola virus disease among children in West Africa. N Engl J Med. 2015;372:1274-1277.
http://www.nejm.org/doi/full/10.1056/NEJMc1415318
http://www.ncbi.nlm.nih.gov/pubmed/25806936?tool=bestpractice.com
Patients are not considered infectious until they develop symptoms. Human infection carries a high case fatality rate depending on the Ebola virus species and quality of supportive care available.

Ebola virus infection is part of the group of conditions known as viral haemorrhagic fevers, and was formerly known as Ebola haemorrhagic fever.

Treatment algorithm

Contributors

Liverpool School of Tropical Medicine and Royal Liverpool University Hospital

Liverpool

UK

Disclosures

NJB is an author of several references cited in this monograph. NJB is partially supported by the National Institute of Health Research Health Protection Unit in Emerging and Zoonotic Infections at the University of Liverpool and Public Health England. He is affiliated with the Liverpool School of Tropical Medicine. Views expressed in this monograph are those of the contributor and do not necessarily represent the official position of the National Health Service, the National Institute for Health Research, the Department of Health, or Public Health England.